Mechanical face seals are commonly used to provide a seal between a stationary housing and a rotating shaft. Such seals include a rotating ring mounted on the shaft and a stationary ring mounted on the housing. Either the stator or the rotor is biased toward the other to provide a biased seal therebetween.
In a fluid pump, such as a compressor, the seal between the housing and the shaft must inhibit the loss of high pressure fluid (e.g., oil) from the housing. To accomplish this, some seals include spiral grooves on the face of either the stator or the rotor. The grooves are angled relative to the radius and circumference of the rotating shaft and, when the rotor is rotating, the grooves pressurize the low pressure fluid and "pump" the fluid between the stator and the rotor. This pumping of the low pressure fluid toward the high pressure fluid substantially prevents loss of high pressure fluid. In order to prevent contamination of the high pressure fluid, an inert buffer fluid is provided as the low pressure fluid. U.S. Pat. No. 5,375,853 discloses a seal of this type.
In another design, grooved face seals are used in pumps to provide a seal between a high pressure gas (e.g., a combustible gas) and the ambient atmosphere. In this situation, two seals are commonly used. A grooved inner seal pumps the high pressure gas to an intermediate chamber, and a grooved outer seal pumps from the intermediate chamber to the atmosphere. The intermediate chamber routes the high pressure gas to a flare stack where the pumped gas is burned. The amount of high pressure gas that is lost through the outer seal is thereby minimized. An example of this type of seal is disclosed in U.S. Pat. No. 5,217,233.